Investigating a Liver Fat: Arterial Stiffening Pathway in Adult and Childhood Obesity.
Rider OJ., Banerjee R., Rayner JJ., Shah R., Murthy VL., Robson MD., Neubauer S.
OBJECTIVE: To investigate the relationship between hepatic fat content, circulating triglyceride levels and aortic stiffness in adult and childhood obesity. APPROACH AND RESULTS: Seventy-seven adults and 18 children across a wide range of body mass index (18.5-52.6 kg/m(2); percentile 8-100) with no identifiable cardiac risk factors underwent; 1H- magnetic resonance spectroscopy to quantify hepatic fat content and magnetic resonance imaging to assess aortic pulse wave velocity (PWV) and regional distensibility. In adults, multivariable regression showed age (β=0.09; P=0.02), liver fat (β=2.5; P=0.04), and serum triglyceride (β=0.47; P=0.01) to be independent predictors of PWV. Age and blood pressure-adjusted, moderated regression showed that 43% of the total negative effect of hepatic fat on PWV is attributable to indirect effects via increased triglyceride (P=0.005). In addition, regional distensibility was positively correlated with hepatic fat (ascending; r=-0.35; descending, r=-0.23; abdominal, r=-0.41; all P<0.001). Similar to that seen in adults, PWV (r=0.72; P<0.001) and abdominal regional distensibility (r=-0.52; P<0.001) were correlated with liver fat in children. CONCLUSIONS: Increasing age, liver fat, and triglyceride are all related to increased aortic stiffness in adults. Even when controlling for the effects of age and blood pressure, hepatic fat has a negative effect on PWV, with substantial indirect effect occurring via increased circulating triglyceride level. This relationship between hepatic fat and aortic stiffness occurs early in the obesity process and is also seen in children. As such, hepatic fat content is a potential therapeutic target to treat the elevated vascular risk in obesity.